Recently, wireless data, entertainment and mobile communications technologies have become increasingly prevalent, particularly in the household environment. The convergence of these wireless data, entertainment and mobile communications within the home and elsewhere has created the need for merging many disparate devices into a single wireless network architecture capable of seamlessly supporting and integrating the requirements of all of these devices. Seamless connectivity and rapid transfer of data, without confusing cables and wires for various interfaces that will not and cannot talk to each other, is a compelling proposition for a broad market.
To that end, communication industry consortia such as the MultiBand OFDM Alliance (MBOA), Digital Living Network Alliance (DLNA) and the WiMedia Alliance are establishing design guidelines and standards to ensure interoperability of these wireless devices. The WiMedia Alliance has promulgated such a guideline and standard, hereinafter referred to as the WiMedia Specification.
Although it began as a military application dating from the 1960s, UWB has recently been utilized as a high data rate (480+ Mbps), short-range (up to 20 meters) technology that is well suited to emerging applications in the consumer electronics, personal computing and mobile markets. When compared to other existing and nascent technologies capable wireless connectivity, the performance benefits of UWB are compelling. For example, transferring a 1 Gbyte file full of vacation pictures from a digital camera to a computer take merely seconds with UWB compared to hours using other currently available, technologies (i.e. Bluetooth) and consume far less battery power in doing so.
In typical UWB, data is transmitted using a plurality of signals, the plurality of signals are transmitted using a plurality of frequencies within a UWB frequency range. The signal transmitted at any one frequency is referred to as a tone. Thus, a typical UWB signal is comprised of a plurality of tones, each tone associated with a particular frequency.
Because UWB, by definition, is spread over a broad spectral range, the power spectral density of a signal utilized by a UWB device is usually very low, and hence, usually results in low incidence of interference with other systems which may be utilizing the same bandwidth as the UWB device or system.
Power spectral density, however, may be a function of distance. Consequently, if a UWB device is in close proximity to another wireless system, the potential for interference between the UWB device and the wireless system cannot be neglected.
Additionally, there may be select frequency bands within a UWB channel where it is necessary to explicitly suppress emissions. For example, some existing UWB spectrum allocations encompass frequencies used by C-Band satellite downlinks. Thus, it may be necessary in certain regulatory domains for UWB systems to defer to these and other types of systems.
Thus, the ability to control the shape and energy of a UWB signal is important for many reasons, including regulatory, commercial and interference. Therefore, there is a need to develop methods and techniques for controlling or shaping the power spectrum of a UWB signal or waveform.